Fishes often die after extreme labour…

A fish consist depending to the species for 40 to 65% out of white mussclemass. Changes in metabolism occurring after for example exhaustion, extreme labour or handling can be determining if a fish survives a stressful situation. It is known from the angling sport that salmonids after catching and a fight with the angler that may take from a few minutes up to an hour or so, 40 – 50% of these fishes will survive. From professional fisherman, at sea it is know that fishes caught as side catch, after returning in to the sea, a large number of them do not survive. In the ornamental fish trade, we experience regularly this problem when we have to collect fishes from aquaria.  

Scientific research showed that mortality by exhausted animals not only caused by soured muscle tissues, as the intracellular PH after exhaustion lies around the 6,6 – 6,7. Noticeable is that animals with higher energy levels in their cell tissues, are better equipped to recover. The removal of toxic waist like lactate takes energy; it is possible that animals will die by energy shortage because they are not able to remove waist materials from their tissues. This souring may stay to long in the tissues what may cause the death of the fish involved.

Many hobbyists catching fishes from their aquaria use to often to small nets, or they have to empty the aquarium complete to catch the specific selected fishes. This caused extreme stress by these fishes. Further there is the problem that the average hobbyist is changing far to less water at a time, and the time between water changes is to long. This may results in sometimes-extreme pollution values, what the condition of the fishes not positive improves.

When you buy fishes in a shop, the dealer uses mostly a large net to collect the wanted fish. This causes as less as possible stress in the shortest possible collection time. Further, due to the larger numbers of fishes the dealer is changing more often larger volumes of water. When you buy a fish it should be packed in a plastic bag with water again and than, we have to ad new water to the system again.  

When we take animals from hobbyists we do not know how they where catched from their aquarium, we certainly know that 50 up to 60% of the fishes are not surviving. This is one of the main reasons dealers are not prepared to pay for fishes, which they get back from hobbyists.  

Literature cited:

Aqua Cultuur Nr. 4, september 2004, page 14 - 21  

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